1. Field of the Invention
This invention relates to adhesive compositions. This invention particularly relates to adhesive compositions including block copolymers.
2. Background of the Art
The preparation of block copolymers of mono alkenyl arenes and conjugated dienes is well known. One of the first patents on linear ABA block copolymers made with styrene and butadiene is U.S. Pat. No. 3,149,182. Uses for the block copolymers include injection molding, extrusion, blow molding, adhesives, and the like. These polymers have also been used in applications such as the modification of bitumen for the production of roofs and roads. Other uses of block copolymers include the production of films, fibers, non-woven fabrics.
One early example of such a block copolymer is in U. S. Pat. No. 4,188,432 to Holden, et al. Disclosed therein are shaped articles which are resistant to attack by fatty substances consisting essentially of high impact styrene-butadiene graft copolymer or a mixture thereof with no more than about 55% styrene homopolymer. The shaped articles also include small proportions of polyethylene or polypropylene and of a block copolymer X-Y-X in which each X is a polystyrene block of about 5,000 to 10,000 molecular weight and Y is a hydrogenated polybutadiene block of 25,000 to 50,000 molecular weight.
Adhesive compositions based on styrenic block copolymers as thermoplastic elastomer components are well known in the art. These compositions are disclosed to be useful for preparing pressure sensitive adhesives for industrial tapes, packaging tapes and labels, and in multipurpose hot-melt adhesive compositions which may be used to bond or construct articles in the manufacture of disposable soft goods, such as diapers, feminine care articles, surgical drapes and the like. Styrene-isoprene-styrene block copolymers and styrene-butadiene-styrene block copolymers are widely used in these adhesive compositions.
EP-1331000258 to Muyldermans, et al., discloses a pressure sensitive adhesive composition comprising, calculated on 100% of all the components, 30 to 45% of one or more block copolymers of structure ABA or (AB) (n)-X or ABABA or BABAB or ABAB were each A independently is a polymer block of a monoalkenyl arene; each B block independently is a polymer block of a conjugated diene, or a mixture of conjugated dienes, hydrogenated in such a manner to leave a residual unsaturation content below 20%. It is also disclosed therein that the adhesive can include an optional and additional component such as a polyolefin.
U.S. Pat. No. 6,657,000 to De Keyzer, et al., also discloses an adhesive including a block copolymer. This reference discloses a hot melt pressure sensitive positioning adhesive for use with an absorbent article. The adhesive comprises: (a) from 5 to less than 15 percent by weight of a blend of (i) a hydrogenated styrene-(butadiene or isoprene)-styrene block copolymer having a polystyrene block number average molecular weight of 20,000 or less, and (ii) a homogeneous linear or substantially linear interpolymer of ethylene and at least one C3-C20 alpha olefin having a density from 0.85 to 0.91 grams per cubic centimeter; and (b) from 50 to 80 percent by weight of a tackifying resin and (c) from 5 to 35 percent by weight of a plasticizing oil. The block copolymer of (i) may also be one in which the polystyrene block molecular weight is greater than 20,000.
U. S. Patent No. 6,582,829 to Quinn, et al., discloses a hot melt adhesive composition comprising homogeneous ethylene interpolymer and a block copolymer. The hot melt adhesive composition is one comprising a) from about 5 wt-% to about 50 wt-% of at least one homogeneous linear or substantially linear ethylene/alpha-olefin interpolymer characterized as having a density from 0.850 to 0.965 g/cm3; b) from about 1 wt-% to about 40 wt-% of at least one block copolymer; and c) from about 10 wt-% to about 75 wt-% of at least one tackifying resin. The adhesive is further characterized in that it does not fail cohesively.